function plotData(X, y)
    figure;
    hold on;
    pos = find(y == 1);
    neg = find(y == 0);
    plot(X(pos, 1), X(pos, 2), 'k+', 'LineWidth', 2, 'MarkerSize', 7);
    plot(X(neg, 1), X(neg, 2), 'ko', 'MarkerFaceColor', 'y', 'MarkerSize', 7);
    hold off;
end
